Is this how Oscar campaigns are usually conducted? With the presumptive nominee in a kilt at the lip of a festival stage, asking the crowd, “Does anybody wanna get crazy with me tonight?”

Harvey Weinstein probably wouldn’t do it this way. But then, Jared Leto has never bowed to convention.

The singer of Thirty Seconds to Mars, who headlined 97X Next Big Thing on Saturday at Vinoy Park in St. Petersburg, has entered a new era of his life as an actor-musician, thanks to rave reviews for his tender performance as an AIDS-afflicted transvestite in Dallas Buyers Club. Next week, he could be a Golden Globe nominee for his role as Rayon, the friend and business partner of Ron Woodruff (Matthew McConaughey), and most Oscar oddsmakers think a Best Supporting Actor nod is inevitable.

This is rarefied territory for an actor-musician. If Jared Leto really is now in the same league as all-around talents like Jamie Foxx and Jennifer Hudson, we must reckon with him in a way we never have.

For the past six years, Leto was more rock star than actor, eschewing major film roles to focus on Thirty Seconds to Mars. The alt-rock outfit has been called a Hollywood boy toy’s plaything — some surely still see it that way — but over 15 years and four increasingly ambitious albums, the band has grown into a globe-trotting, platinum-selling musical machine.

Their live shows have a lot to do with that. Though he found fame as dim heartthrob Jordan Catalano in My So-Called Life, Leto has evolved into a fearlessly committed performer, whether as a strung-out junkie in Requiem For a Dream, paunchy killer Mark David Chapman in Chapter 27, a maniacal foot solder in Fight Club or a twitchy, cornrowed crook in Panic Room. At Thirty Seconds to Mars concerts, he has been known to march into the crowd, sprint around the arena, scale the scaffolding of the stage — anything it takes to earn the doubters’ love and faith.

On Saturday, though, Leto largely avoided such shenanigans. Wearing a kilt over pants, a sleeveless tee and dark shades, he paced and twirled around the ample space afforded him at center stage, waving a flag with the band’s triangular logo that he also has tattooed on both forearms.

But on this night he never ventured into the audience (though he did invite several fans on stage), and said little of note beyond praising 97X and offering a litany of empty rock-star platitudes (“We’re gonna jump so high we’re gonna touch the stars” ... “If you’re a dreamer, put your hands in the air” ... “You’ve been an important part of our journey”). There were neon balloons and a cloud of confetti, but it was otherwise a relatively by-the-books performance — about nine or 10 songs with no encore, just Leto sprinting off into the night.

Musically, Thirty Seconds to Mars has pulled away from the raw combativeness of 2005’s A Beautiful Lie (from which Leto played but one song, an acoustic rendition of The Kill) and embraced a soaring sound that aims for the inspirational grandeur of Coldplay or Angels and Airwaves, such as the epic City of Angels, from this year’s Love, Lust, Faith and Dreams; or the surging Kings and Queens from 2009’s This Is War.

Ironically, this is all happening as Dallas Buyers Club spotlights Leto’s ability to go small. Rayon is flirty and cool, but human to the end; it’s a heartbreaking performance that hinges on Leto’s restraint. Thirty Seconds to Mars doesn’t seem to be going away anytime soon, so Leto must now figure out how to live as both an outsized rock star and an actor with Oscar-winning potential.

He does seem committed to both worlds, regardless of what critics on either side might think. As McConaughey says in Dallas Buyers Club, “Sorry, lady, but I prefer to die with my boots on.” Leto’s that way, too. Win or lose at the Oscars, he’s going down his way, wearing a kilt and waving their flag till the end.

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Leto was the headliner at Saturday’s Next Big Thing, but another surprise guest packed just as much of a punch.

An unexpected warmth blazed across Vinoy Park on Saturday, which seemed like a great thing for a December day until most people actually got out there in it. English folk-punk troubadour Frank Turner initially praised St. Pete’s “incredible weather,” but as he hopped and sweltered through a set of bouncy, alt-countryish bar rock, his tune began to change. “I feel like my entire body is melting into a puddle on the ground,” he said.

The weather finally began to make sense just before the sun fell behind the horizon, with reggae-rockers Dirty Heads easing the crowd into a twilight set by emo heroes Jimmy Eat World. Everyman singer Jim Adkins ripped though a chest-pounding set that never paused for a breather, from the propulsive Bleed American and Big Casino to hits Sweetness and The Middle, with a power-pop cover of Wham!’s Last Christmas a welcome seasonal treat.

“At a time when you’re hearing about snow in Vegas and ice storms in Dallas, isn’t this awesome?” Adkins said as soon as the sun went down.

The volume cranked way, way up after dark. Leading into Thirty Seconds to Mars were ’90s grungers Stone Temple Pilots fronted by Linkin Park’s Chester Bennington, who this year replaced Scott Weiland as the band’s semi-full-time singer.

Though Bennington co-fronts one of the world’s most popular hard rock bands, the appeal of singing for Stone Temple Pilots seems pretty obvious. Nothing against Linkin Park, but there, he’s often relegated to the role of Designated Screamer. With Stone Temple Pilots, he and wrap his apocalyptic pipes around the glammy Big Bang Baby, the serpentine Vaseline and the drugged-out blues of Big Empty. The band played hit after hit after hit, with Bennington nailing Weiland’s bluesy, upper-register yowl on each one, and the DeLeo brothers, guitarist Dean and bassist Robert, plowing through a searing Sex Type Thing (the original Blurred Lines!).

“Scott who?!” shouted 97X’s Joel Weiss after the set. “Scott who?!”

Two Florida bands more than acquitted themselves on Saturday night. Ocala’s A Day To Remember, veterans of multiple Next Big Things, delivered a joyous set of pop-metal that was aggro yet melodic, with fans rushing the stage, columns of CO2 and singer Jeremy McKinnon crowdsurfing in a giant inflatable hamster ball. And less than a month after playing their first show, St. Petersburg’s Sleepwave — the new project of former Underoath singer Spencer Chamberlain — showcased a sound not dissimilar to Nine Inch Nails or Linkin Park; think heavy alt-metal with slight industrial and electronic touches.